The present invention relates to a system for transporting workpieces in a forming press, particularly in a multistation press, and, more particularly to a system comprising at least one cross traverse for holding the workpieces, at least one lifting and lowering device operatively connected on at least one end of the at least one cross traverse so that the latter can be oriented in a desired spatial orientation.
A workpiece transport system of this general type is described in DE 44 18 417 A1. In actual use of this known system in a press, however, breakages and other damage to the cross traverse may occur which are usually the result of excessive forces caused by the drives.
Such a destruction of the cross traverses is particularly disadvantageous because, on the one hand, these components are very expensive and, on the other hand, any exchange of the cross traverses represents a considerable time and therefore cost expenditure, particularly because the forming press cannot produce while the exchange is taking place.
An object of the present invention is, therefore, to provide a system for transporting workpieces in a forming press in which the cross traverse is protected from destruction when used in practice.
According to the invention, this object has been achieved by providing that, between the cross traverse and the at least one lifting and lowering device, at least one overload protection device is arranged for cutting the connection between the cross traverse and the at least one lifting and lowering device.
The overload protection device according to the invention ensures the mechanical connection between the at least one lifting and lowering device and the cross traverse in the normal operation of the forming press. In the event of the occurrence of an excessive loading of the cross traverse and thus an unacceptably high force, the overload protection device is triggered and thereby cuts the mechanical connection between the cross traverse and the at least one lifting and lowering device.
In this manner, a protection of the cross traverse is achieved in the event of overloading, whereby damage to the cross traverse can be avoided and, also when unacceptably high forces occur, which would otherwise result in damage to the cross traverse, only an extremely short stoppage time has to be accepted for the entire forming press.
In order to achieve a still better protection of the cross traverse, an advantageous further development of the invention contemplates that the cross traverse is connected at its two ends with a respective lifting and lowering device, in which case one overload protection device respectively is arranged between the cross traverse and the two lifting and lowering devices.
Furthermore, the at least one lifting and lowering device is capable of moving the cross traverse in the horizontal and vertical direction, and the overload protection device has a horizontal-force overload protection element and a vertical-force overload protection element. As a result, the cross traverse is separately protected from horizontal and vertical overloads, whereby a still better protection is obtained for the cross traverse.